The Centre for Environment, Fisheries and Aquaculture Science (Cefas) is an Executive Agency of the Department of Environment, Food and Rural Affairs (Defra), formerly the Ministry of Agriculture, Fisheries and Food (MAFF). It was also known previously as the Directorate of Fisheries Research (DFR). This data policy refers to data collected by the organisation under all titles.

These data have no specific confidentiality restrictions for academic users. However data are restricted for commercial requests and clearance must be obtained by BODC from Cefas before they are released.

Users must acknowledge data sources as it is not ethical to publish data without proper attribution. Any publication or other output resulting from usage of the data should include an acknowledgement.

The recommended acknowledgement is: "This study uses data from the Centre for Environment, Fisheries and Aquaculture Science (Cefas), provided by the British Oceanographic Data Centre."

Niskin Bottle

The Niskin bottle is a device used by oceanographers to collect subsurface seawater samples. It is a plastic bottle with caps and rubber seals at each end and is deployed with the caps held open, allowing free-flushing of the bottle as it moves through the water column.

Standard Niskin

The standard version of the bottle includes a plastic-coated metal spring or elastic cord running through the interior of the bottle that joins the two caps, and the caps are held open against the spring by plastic lanyards. When the bottle reaches the desired depth the lanyards are released by a pressure-actuated switch, command signal or messenger weight and the caps are forced shut and sealed, trapping the seawater sample.

Lever Action Niskin

The Lever Action Niskin Bottle differs from the standard version, in that the caps are held open during deployment by externally mounted stainless steel springs rather than an internal spring or cord. Lever Action Niskins are recommended for applications where a completely clear sample chamber is critical or for use in deep cold water.

Clean Sampling

A modified version of the standard Niskin bottle has been developed for clean sampling. This is teflon-coated and uses a latex cord to close the caps rather than a metal spring. The clean version of the Levered Action Niskin bottle is also teflon-coated and uses epoxy covered springs in place of the stainless steel springs. These bottles are specifically designed to minimise metal contamination when sampling trace metals.

Deployment

Bottles may be deployed singly clamped to a wire or in groups of up to 48 on a rosette. Standard bottles have a capacity between 1.7 and 30 L, while Lever Action bottles have a capacity between 1.7 and 12 L. Reversing thermometers may be attached to a spring-loaded disk that rotates through 180° on bottle closure.

Originator's Protocol for Data Acquisition and Analysis

Samples for chlorophyll and phaeopigment concentration were collected by the Centre for Environment, Fisheries and Aquaculture Science (CEFAS) on a Proudman Oceanographic Laboratory (POL) Oceans 2025 SO11 Coastal Observatory cruise (number 45) in Liverpool Bay and the Eastern Irish Sea. The cruise ran from 20 - 21 June 2007. Samples were collected near-surface from water bottle rosette sampling systems mounted on the lowered CTD at 10 CTD stations.

For each sample, a 250 ml sample is passed through Whatman GF/F filter under low vacuum. The filter paper is folded in half, loosely wrapped in aluminium foil and placed in plastic bag. Samples are stored in this way in a box containing desiccant at -18 °C until analysis. Filters are extracted using 8 ml 90% acetone and measured fluorometrically according to Tett (1987) for chlorophyll-a and phaeopigments. CEFAS use a Turner 10AU field fluorometer, which has been calibrated using a pure solution of chlorophyll-a.

BODC Processing

The data were supplied to BODC as an Excel spreadsheet. This was converted to an ASCII format file for loading into the BODC archive. The variables supplied by the Data Originator were mapped to BODC parameter vocabularies as follows:

Originator's Parameter

Units

Description

BODC Parameter Code

Units

Comments

CHLOROPHYLL

µg l -1

Concentration of chlorophyll-a {chl-a} per unit volume of the water body [particulate >GF/F phase] by filtration, acetone extraction and fluorometry

CPHLFLP1

mg m -3

µg l -1 = mg m -3

-

-

Concentration standard deviation of chlorophyll-a {chl-a} per unit volume of the water body [particulate >GF/F phase] by filtration, acetone extraction and fluorometry

CLSDFLP1

mg m -3

Calculated by BODC

PHAEOP

µg l -1

Concentration of phaeopigments per unit volume of the water body [particulate >GF/F phase] by filtration, acetone extraction and fluorometry

PHAEFLP1

mg m -3

µg l -1 = mg m -3

-

-

Concentration standard deviation of phaeopigments per unit volume of the water body [particulate >GF/F phase] by filtration, acetone extraction and fluorometry

PHSDFLP1

mg m -3

Calculated by BODC

The data were loaded into the database by matching the sample's station identifier and depth with the information already held in the database for this cruise. Records for this cruise indicated that two rosette bottles, numbers 10 and 11, were used to obtain water samples at the surface for CEFAS at each station. For cast C001, the chlorophyll and phaeopigment sample was taken from rosette bottle 11. For all other casts except C002 and C031, the samples were taken from rosette bottle 10.

For casts C002 and C031 there is insufficient information in the metadata supplied by CEFAS to enable BODC to identify which of bottles 10 or 11 were the source of the samples. BODC arbitrarily linked the chlorophyll and phaeopigment data for C002 and C031 to rosette bottle 10 as this is the source of the majority of the samples for PD13_07.

In all cases, the data supplied were multiple replicates for each station. BODC calculated the mean value and standard deviation for these data and loaded them into the database.

Sustained, systematic observations of the ocean and continental shelf seas at appropriate time and space scales allied to numerical models are key to understanding and prediction. In shelf seas these observations address issues as fundamental as 'what is the capacity of shelf seas to absorb change?' encompassing the impacts of climate change, biological productivity and diversity, sustainable management, pollution and public health, safety at sea and extreme events. Advancing understanding of coastal processes to use and manage these resources better is challenging; important controlling processes occur over a broad range of spatial and temporal scales which cannot be simultaneously studied solely with satellite or ship-based platforms.

Considerable effort has been spent by the Proudman Oceangraphic Laboratory (POL) in the years 2001 - 2006 in setting up an integrated observational and now-cast modelling system in Liverpool Bay (see Figure), with the recent POL review stating the observatory was seen as a leader in its field and a unique 'selling' point of the laboratory. Cost benefit analysis (IACMST, 2004) shows that benefits really start to accrue after 10 years. In 2007 - 2012 exploitation of (i) the time series being acquired, (ii) the model-data synthesis and (iii) the increasingly available quantities of real-time data (e.g. river flows) can be carried out through Sustained Observation Activity (SO) 11, to provide an integrated assessment and short term forecasts of the coastal ocean state.

Overall Aims and Purpose of SO 11

To continue and enlarge the scope of the existing coastal observatory in Liverpool Bay to routinely monitor the northern Irish Sea

To develop the synthesis of measurements and models in the coastal ocean to optimize measurement arrays and forecast products. Driving forward shelf seas' operational oceanography with the direct objective of improving the national forecasting capability, expressed through links to the National Centre for Ocean Forecasting (NCOF)

To exploit the long time-series of observations and model outputs to: a) identify the roles of climate and anthropogenic inputs on the coastal ocean's physical and biological functioning (including impacts of nutrient discharges, offshore renewable energy installations and fishing activity) taking into consideration the importance of events versus mean storms / waves, river discharge / variable salinity stratification / horizontal gradients; b) predict the impacts of climate change scenarios; and c) provide new insights to Irish Sea dynamics for variables either with seasonal cycles and interannual variability, or which show weak or no seasonal cycles

To provide and maintain a 'laboratory' within which a variety of observational and model experiments can be undertaken (Oceans 2025 Themes 3, 6, 8, 9), including capture of extreme events

Demonstrate the value of an integrated approach in assessment and forecasting

Demonstrate the coastal observatory as a tool for marine management strategies through collaboration with the Environment Agency (EA), Department for Environment, Food and Rural Affairs (DEFRA), Joint Nature Conservation Commmittee (JNCC), English Nature (EN), Department of Agriculture and Rural Development (DARD), and Local Authorities, providing management information pertinent to policy (e.g. Water Framework Directive)

Please note:the supplied parameters may not have been sampled from all the bottle firings described in the table above. Cross-match the Sample Reference Number above against the SAMPRFNM value in the data file to identify the relevant metadata.